Adjusting Wheel Circumference On Intuvia

[sammcneill]

Hi,

Many others have discussed the disparity in speed between Bosch headunit speed output vs GPS recorded speed. Solution is to change the wheel circumference as per JV Bulman's post

Disparity between Kiox speed & GPS

you don't want to use a phone app to compare. my Apple Watch or phone is off a fair amount from my gamins.

forums.electricbikereview.com

My SC2 Bosch Intuvia is consistently 2-3kph faster than my Garmin so I finally delved into the settings to change the setting - it was on 2190mm by default.

I'm running Super Moto X in a 27.5 x 2.35 so I went and found circumference here:

Tire Dimensions - Schwalbe Professional Bike Tires

Even when I changed it to 2240 it seems to have made no difference to the accuracy - it's still consistently 'faster' - It's not the end of the world but just frustrating I can't seem to get this dialled in more accurately.

Any tips?

Cheers
Sam

 

[fooferdoggie]

Hi,

Many others have discussed the disparity in speed between Bosch headunit speed output vs GPS recorded speed. Solution is to change the wheel circumference as per JV Bulman's post

Disparity between Kiox speed & GPS

you don't want to use a phone app to compare. my Apple Watch or phone is off a fair amount from my gamins.

forums.electricbikereview.com

My SC2 Bosch Intuvia is consistently 2-3kph faster than my Garmin so I finally delved into the settings to change the setting - it was on 2190mm by default.

I'm running Super Moto X in a 27.5 x 2.35 so I went and found circumference here:

Tire Dimensions - Schwalbe Professional Bike Tires

View attachment 165901

Even when I changed it to 2240 it seems to have made no difference to the accuracy - it's still consistently 'faster' - It's not the end of the world but just frustrating I can't seem to get this dialled in more accurately.

Any tips?

Cheers
Sam

just change the tire size smaller each ride till it is. but going by the garmin is not great either. better to sue a road mile marker.

 

[sammcneill]

oh, so I need to be reducing the circumference to lower the reported speed?

 

[fooferdoggie]

oh, so I need to be reducing the circumference to lower the reported speed?

yes. I know it does not seem right. your never going to get perfection.

 

[Stefan Mikes]

oh, so I need to be reducing the circumference to lower the reported speed?

Yes. All your e-bike knows is the number of the rear wheel revolutions per minute. The e-bike "computer" multiplies that value by the given wheel circumference to give the distance ridden, which translates to the distance ridden in an hour (speed). The lower the wheel circumference, the shorter reported ride distance, and the speed.

If your Bosch e-bike could be connected to the Garmin (it cannot but cheaper Specialized or Giant e-bikes can), then you would either enter the custom wheel circumference there, or give Auto, and the Wheel Circumference would be automatically calculated there against the GPS.

Note: As one of the users carefully explained it, manipulating the Wheel Circumference on a Bosch e-bike affects the reported ride distance and speed but the assistance speed cut-off is not affected, and the motor will cut off at the speed based on the Wheel Circumference hard-coded in the motor.

 

[sammcneill]

Well turns our smallest wheel circumference I can enter is 2080 - and made no difference to reported speed vs Garmin GPS